Complex spatial light modulator and holographic 3D image display device having the same

Abstract

A complex spatial light modulator includes a polarization-phase modulator for separating an incident beam into a first beam having a first polarization and a first phase, and a second beam having a second polarization and a second phase, and for outputting the first beam and the second beam; and a beam synthesizer including a prism structure formed of an optical anisotropic material having a first refractive index with respect to the first beam having the first polarization and having a second refractive index, different form the first refractive index, with respect to the second beam having the second polarization, where the beam synthesizer combines the first beam and the second beam.

What is claimed is: 
     
       1. A complex spatial light modulator comprising:
 a polarization-phase modulator which modifies an incident beam of light and separates the incident beam of light into a first beam having a first polarization and a first phase, and a second beam having a second polarization and a second phase, and which outputs the first beam and the second beam; and 
 a beam synthesizer comprising a prism structure formed of an optical anisotropic material, the optical anisotropic material having a first refractive index with respect to the first beam having the first polarization and a second refractive index, different from the first refractive index, with respect to the second beam having the second polarization, wherein the beam synthesizer combines the first beam and the second beam and outputs a beam; 
 wherein the prism structure has a first inclined surface having a normal that is inclined with respect to an optical axis of the incident beam, and a second inclined surface that is parallel to the first inclined surface and that faces the first inclined surface, the prism structure being a single structure; and 
 wherein the optical anisotropic material fills a space between the first inclined surface and the second inclined surface. 
 
     
     
       2. The complex spatial light modulator of  claim 1 , further comprising a first polarizer, disposed on an optical path before the polarization-phase modulator, which transforms a polarization of a beam incident thereon into a beam having the first polarization. 
     
     
       3. The complex spatial light modulator of  claim 1 , wherein the polarization-phase modulator comprises:
 a phase-type spatial light modulator comprising a first cell that modulates a phase of a portion of the incident beam incident thereon and outputs a beam having the first phase and a second cell that modulates a phase of a portion of the incident beam incident thereon and outputs a beam having the second phase; and 
 a pattern rotator comprising a first region that corresponds to the first cell and a second region that correspond to the second cell, wherein one of the first region and the second region is a rotator that rotates a polarization of a beam incident thereon having the first polarization and outputs a beam with the second polarization. 
 
     
     
       4. The complex spatial light modulator of  claim 1 , wherein the first refractive index is substantially the same as a refractive index of air, and the second refractive index is greater than 1. 
     
     
       5. The complex spatial light modulator of  claim 4 , wherein an angle by which the normal of the first inclined surface is inclined with respect to the optical axis of the incident beam is such that an optical path of the second beam is changed due to refraction at the first inclined surface and refraction at the second inclined surface, and thus the optical path of the second beam is modified, by the beam synthesizer, to be the same as an optical path of the first beam which passes through the first inclined surface and the second inclined surface without refraction. 
     
     
       6. The complex spatial light modulator of  claim 3 , wherein the beam synthesizer further comprises:
 a first prism sheet comprising at least one prism that has a light-incident surface which is normal to the optical axis of the incident beam, and an inclined surface which abuts the first inclined surface of the prism structure and is inclined with respect to the light-incident surface of the first prism sheet; and 
 a second prism sheet that is spaced apart from the first prism sheet, wherein the second prism sheet comprises at least one prism having an inclined surface which faces the inclined surface of the first prism sheet and abuts the second inclined surface of the prism structure and is inclined with respect to the light-incident surface of the first prism sheet, and a light-exit surface which is parallel to the light-incident surface of the first prism sheet; 
 wherein each of the first prism sheet and the second prism sheet are formed of an optical isotropic material, and a refractive index of the first prism sheet is substantially equal to a refractive index of the second prism sheet. 
 
     
     
       7. The complex spatial light modulator of  claim 6 , wherein the first refractive index is substantially the same as the refractive index of the first prism sheet, and the second refractive index is different from the first refractive index. 
     
     
       8. The complex spatial light modulator of  claim 7 , wherein an angle by which the first inclined surface of the prism structure and the second inclined surface of the prism structure are inclined with respect to the light-incident surface of the first prism sheet is such that an optical path of the second beam is changed due to refraction at the first inclined surface of the prism structure and refraction at the second inclined surface of the prism structure, and thus the optical path of the second beam is modified, by the beam synthesizer, to be the same as an optical path of the first beam that passes through the first inclined surface of the prism structure and the second inclined surface of the prism structure without refraction. 
     
     
       9. The complex spatial light modulator of  claim 2 , further comprising a second polarizer, disposed on the optical path after the beam synthesizer, which transforms the combined beam into one of:
 a beam having a third polarization that is inclined by 45 degrees with respect to each of the first polarization and the second polarization, and 
 a beam having a fourth polarization which is perpendicular to the third polarization. 
 
     
     
       10. A holographic three-dimensional (3D) image display device comprising:
 a light source unit; 
 the complex spatial light modulator of  claim 1 ; and 
 a control unit which controls the complex spatial light modulator, to modulate a beam from the light source unit according to 3D image information. 
 
     
     
       11. The holographic 3D image display device of  claim 10 , wherein the light source unit outputs a beam that is polarized in the first polarization direction. 
     
     
       12. The holographic 3D image display device of  claim 10 , further comprising an imaging optical unit that comprises one or more lenses which magnify or to reduce an image formed by the complex spatial light modulator.